Dr. Julie, a.k.a. Scientific Chick, brings you insights into what's happening in the world of life sciences. Straight from the scientific source, relevant information you should know about, in plain language.

Wednesday, August 26, 2009

Dating advice websites abound with many different kinds of advice: good advice (don’t pick your nose), strange advice (date according to your blood type), not so good advice (Leos dating Leos need to hire domestic helpers). One suggestion that seems to pop up quite frequently is to mimic the body language of your date. He picks up his drink for a sip, you pick up yours. He strokes his hair, you stroke yours. He picks his nose, you pick your nose. You get the idea. As it turns out, in a social interaction context, we humans tend to unintentionally imitate what others are doing. Think of this as a team-building exercise: it’s a behavior that helps establish rapport, empathy and other fuzzy feelings toward each other.

A recent publication in the journal Science shows that behavior matching leading to increased rapport is not exclusive to humans, and it can also occur between different species.

The study looks at capuchin monkeys, a very social primate species. During the experiments, the monkey is given a ball to play with. On either side of the monkey’s cage stands an experimenter. One experimenter is mimicking what the monkey is doing with the ball (poking it, pounding it against the wall, trying to eat it… Mmmmm…), while the other experimenter is also playing with the ball, but not mimicking the monkey. The researchers show that not only do the monkeys look at the imitators more, they also spend more time hanging out close to the imitators and prefer to interact with the imitators in a food exchange game. The authors also did an important series of control experiments to show that these effects were not due to the monkeys perceiving more attention from the imitators.

So why are we subconsciously hard-wired to constantly be playing Simon Says? It is thought that the positive feelings resulting from behavior matching played an important role in human evolution by leading to higher levels of tolerance and by preventing aggressive behavior (to put it simply, by preventing us from beating each other up). The same principle probably applies to primates, and the empathic connection that results from imitation may explain the altruistic tendencies observed in the behavior of capuchin monkeys.

Next time you catch yourself winking back at someone who winked at you, or laughing at a joke you didn’t get because everyone else is laughing, keep in mind it’s for the greater good. After all, even monkeys know that imitation is the sincerest form of flattery.

Scientific Chick readers applying their new found knowledge(Image from Loldogs)

Thursday, August 13, 2009

In a biological context, rationality means that when animals (including humans) are making a decision, they choose the option that maximizes their fitness benefit. For example: my cat, Mr. Minou, prefers to eat canned food rather than grass. Canned food provides him with more nutrients, more protein, and more energy than grass: it has a fitness benefit for Mr. Minou. Even if he is presented with a third option, say, dry cat kibbles, Mr. Minou stills prefers canned food, because it still has the highest fitness benefit (and, obviously, kibbles taste gross).

Pretty straightforward so far. So, being the advanced species we are, humans must be rational beings, right?

Wrong.

Here is another example. Let’s say you’re shopping for a new house. You have two equally important criteria for your new house: it must have big windows to get lots of natural light in, and it must have a big garage to store all your stuff. There are two houses on the market. House A has big windows but a small garage. House B has a big garage but small windows. Rationally, humans in this position have a 50% chance of picking either house.

Suddenly, a third house is made available on the market. House C has big windows, but NO garage. In a situation like this, humans overwhelmingly put rationality aside and shift their pick to house A with the large windows but the small garage, because the perceived value of house A increased when comparing it with other available houses. However, houses A and B have unchanged value!

The reason for this shift is that as decision-makers, we don’t assign absolute values to options, we assign relative values. We like to compare. And comparing can be misleading.

Recently, two American researchers wondered about the rationality of collective animals, such as ants. The researchers figured that just as choices we make result from the complex interactions of many brain cells, the decisions that an ant colony makes might similarly stem from a complex network of interacting insect. Ant societies act as unitary decision-makers, jointly deciding on things like a single travel direction, or a nest site. The researchers decided to take advantage of the ants’ nest-seeking strategies to test their rationality.

The ants in the study live in natural holes like hollow branches, and are able to emigrate to a new nest if their current nest is damaged. Colonies seeking a new nest reach consensus on the better site among the new options based on entrance size, cavity dimensions, interior light level, etc. The way a colony reaches consensus is fascinating: a few scout ants head out to assess the quality of potential homes. When a scout finds a potential new home, it leaves to recruit more scouts, who will then recruit more scouts, and so on. The strength of this technique lies in the key fact that the higher the quality of the nest an ant finds, the faster it will recruit other ants. Eventually, a threshold of recruiting is reached, and non-scout ants are recruited and eventually the entire ant colony is moved.

The researchers first established that ant colonies prefer nests that have small openings and low inside light levels. They then assessed the susceptibility of ant colonies to irrationality by comparing the colonies’ preference for new nests with different attributes in a very similar way to my house example: nest A has a dim interior but a large entrance size, and nest B had a brighter interior but a small entrance size. In this case, the ant colonies showed no preference for either site, which is very rational of them.

The researchers then added one of two decoy nests. Decoy nest A2 was just as dim as nest A, but had an even larger entrance diameter. Decoy nest B2 had the same entrance diameter as B but was even brighter than B. In summary, each decoy nest had a good feature equivalent to that of A or B, and the other feature was worse.

Well, the study suggests that we should turn to ants for real estate advice: the presence of either decoy did not affect the proportion of colonies choosing A or B. This means that even with the decoy, the ant colonies recognized that A and B had equal fitness values, and that the option of the decoy did not change the fitness values of the original nest sites.

So what is the ants’ secret for being so rational? The most plausible explanation is that for the most part, each scout ant only visits one site. If it’s good, it recruits, and if it’s crummy, it moves on. No comparing with the one next door. In this case, the fact that individuals in the decision-making strategy lack either the opportunity or the ability to compare all the options offers some protection against irrational, fitness-reducing errors.

Is this relevant for us, other than the piece of humble pie we must eat when realizing that ants can be more rational than we are? Well, when faced with a decision, it can be helpful to remember to evaluate each option for its absolute value, and not its relative value.

Mr. Minou himself occasionally forgoes rationality and chooses to eat grass. I suspect he only does it for the pleasure of watching me wash puke from the floor afterwards. Maybe in some twisted way, making sure I clean up after him confers him some kind of fitness benefit…

Tuesday, August 4, 2009

Not exactly a surprise, I know, but I didn’t mean you and me are getting older. I meant we are getting older, as a population. In 2001, one Canadian in eight was aged 65 or older. By 2026, one in five will be 65 or older. So what should we do with an increasingly aged population? Well, this being a North American consumer culture, the sensible thing to do is try to sell them stuff. I mean, think of the size of the market!

Right now, a significant amount of research is being devoted to aging. The main focus is to try to slow down aging (partly by developing marketable supplements and such). As some of you might know, even my own PhD thesis project is on how to slow aging in the brain. Loyal readers of ScientificChick.com will also be aware of recent articles about caloric restriction, a potential way to keep old age at bay. Thankfully, a recent publication in Nature suggests a much easier way to live longer: forget starvation, all you have to do is pop a(nother) pill!

In this article, American researchers show that mice that eat rapamycin supplements starting at 600 days of age (senior citizens in mouse years) live longer, up to 14% longer for females and 9% longer for males. What’s more, rapamycin supplementation did not change the causes of death. The researchers propose that this drug could be acting by postponing death from cancer, by delaying mechanisms of aging, or both.

How does rapamycin work? Well, as you might expect with a miracle drug like this, we’re not really sure. Rapamycin is an inhibitor of a pathway called mTOR. The mTOR pathway has many functions in your cells, like coordinating the survival response arising when there are changes in nutrient and energy availability, and dealing with potentially deadly stresses, such as oxidative stress (the kind of stress fancy juices packed with antioxidants are supposed to battle). Since the mTOR pathway acts kind of like a central sensor of cell health, it makes sense that it would be implicated in regulating lifespan. Exactly how rapamycin is working its magic, though, is probably what the researchers are trying to figure out for their next article.

Could the increase in longevity following rapamycin supplementation be related to the effects seen with caloric restriction (the “eat less, live longer” paradigm)? Well, mice on rapamycin show no change in body weight, so we know the drug is not acting through a caloric restriction mechanism. The converse, however, may be true: it is thought that the beneficial effects of diet restriction may also be due to an inhibition of the mTOR pathway.

So don’t throw out the double-stuffed Oreos just yet, but don’t eat half the box either: rapamycin pills for humans won’t be on the shelves tomorrow. While mTOR inhibitors are currently being used to treat a few conditions (transplant rejection and some cancers, for example), there’s still a lot of work to do to tease out all the potential interactions and side effects.

Longevity in pill form? To me, it would feel like cheating the system. And if there’s one thing we keep learning over and over in the life sciences, it’s that trying to cheat Mother Nature always has some unintended consequences.

About Me

Dr. Julie is an Assistant Professor of Neurology at the National Core for Neuroethics and the Djavad Mowafaghian Centre for Brain Health at the University of British Columbia. She holds a PhD in Neuroscience.